Work is continuing in two directions: The isolation and characterization of a glycoprotein secreted into the medium upon incubation of mouse skin papillomas when treated with retinoic acid. A different glycoprotein is secreted from carcinomas. The second approach is the kinetics and mechanism of the induction of fibronectin in mouse skin papillomas when treated with retinoic acid, accompanied by the suppression of ornithine decarboxylase and collagenase induction by the carcinogen.